Electric drive machines may be designed to provide combinations of electric and/or internal combustion power to the machines' drivetrain. Machines increasingly use electric drive systems to provide propulsion for the machine. For example, passenger vehicles may use a hybrid drive system in which a traditional gasoline powered engine and an electric motor are both used to provide propulsion for the vehicle. Machines, such as, for example, off-highway vehicles, may use a diesel-powered engine to drive a generator, which provides electric power to an electric motor. The electric motor is typically configured to provide propulsion for the machine by driving the wheels or travel mechanisms of the machine.
In addition, braking systems may take advantage of components in electric drive systems, including the electric motor, to provide braking for machines. Electric drive machines may require the use of systems for controlling the power produced by the electric motor and/or the engine. Conventional control systems for electric drive machines use various machine operating conditions and parameters to adjust the operations of the machine's motor to increase the performance efficiency of the machine. For example, the control system may allow an operator to interface with the electric drive machine to perform various machine operations, including driving the machine in forward and reverse driving directions.
In certain situations, the operators operating the electric drive machine may desire to change the driving direction of the machine when in motion. For example, the operator may want to change the driving direction of the electric drive machine moving in reverse to forward. In some circumstances, the operator may want to change directions relatively quickly. The electric drive system, however, encounters problems when attempting to change the driving or propulsion direction of the machine if the power required to change the direction of the machine is too high. For example, attempting to change the driving direction before the power required to change the driving direction is appropriately low may lead to comparatively high currents passing through the electric drive system, which may damage some of the electric drive components. To overcome this problem, the operator may have to engage the brake system, for example, by depressing a service brake pedal, wait for the machine to stop, then engage an accelerator pedal while releasing the service brake pedal.
There are prior art systems that include control systems for controlling a method to reverse the driving direction of a vehicle in motion. One such system is described in U.S. Pat. No. 6,910,988 to Carlsson (hereinafter, “Carlsson”), which discloses a method and apparatus for reversing the driving direction of a vehicle in motion. Carlsson's system, however, which is essentially a mechanical drive system, does not address the problems encountered when attempting to change the driving direction of the electric drive machine before the power required to change the driving direction of the machine is appropriately low.
The methods and systems consistent with the disclosed embodiments are directed to overcoming one or more of the problems set forth above and/or other problems in the art.